Sickly-Sweet Obsession
by m a q u i r a
Summary: Quiet, studious Tom Riddle thirsts after an older student—Gryffindor's Quidditch Captain, Harry Potter. His crush is common knowledge, and even Harry finds it cute… at first. Possessiveness spawns monstrosities. Tom does all within his power to mess with Harry's dating life. And one seemingly harmless crush spirals into something darker, begetting deadly consequences.


Hello! This is the first story I've actually planned from beginning to end (I even wrote the final scene?) so I'm excited for where this will be going.

**Full Summary:**

Quiet, studious Tom Riddle spends his first year thirsting after an older student—Gryffindor's Quidditch Captain, Harry Potter. His crush is common knowledge, and even Harry finds it cute… at first.

Possessiveness spawns monstrosities. Tom does all within his power to mess with Harry's dating life. And one seemingly harmless crush spirals into something darker, begetting deadly consequences.

But that isn't where the story ends.

This is the tale of two men who spend their lives stalking each other: one out of twisted love, the other out of passionate hatred—and both, out of pure obsession.

* * *

_Part I: Tom_

The first time Tom Riddle laid eyes on Harry Potter was in his first year Potions class.

He was three months into the school year and he'd already been called Slytherin's latest _mudblood _more times than he cared to keep track of. It was a word eleven-year-old Tom didn't fully understand—and yet, it sounded strangely similar to what the orphanage kids had been calling him his entire life.

_Freak._

And so, in a class where potions were prepared in pairs, Tom worked alone. Both by choice and by nature.

As he'd entered the classroom for the last time that week, he had noted the ease with which partners were chosen. The laughter and camaraderie exchanged by his peers, the smiles and smirks hiding inside jokes—as if they'd known each other for years instead of weeks.

_Friendship. _A strange and unfamiliar concept he'd long since stopped dwelling on.

But no matter—Tom was studious. He was powerful. And he was determined to prove his prowess in every sense of the word, starting with his performance in classes.

Needless to say, he was turned away from the cauldron, peering avidly at the fine print of his textbook for the next steps, when someone entered the classroom… twenty minutes after Potions had begun.

"Professor Slughorn!" a voice called out jovially. It was youthful and boyish, yet far lower than any first year's had the right to be.

Professor Slughorn looked up from the vials he'd been setting up on his desk. His mouth quirked up in amusement even as he pushed his glasses up his nose, looking sternly in the man's direction.

"Mr. Harry Potter. What are you doing in my first year Potions class?"

The newcomer's footsteps grew louder as they came closer. As he passed Tom, a weird bristling sensation tingled against Tom's legs, distracting him from his current count of stirs.

Pursing his mouth in annoyance, Tom narrowed his eyes in the direction of the newcomer.

And then, he simply… continued to stare.

Because the first thing that struck him about Harry Potter wasn't his green eyes, or his tousled mess of hair. Or even his toned, tan body, so much larger than Tom's own… the sleek muscles of his arms visible underneath soaked Quidditch gear, as if he'd just finished a morning fly.

No.

It was his stupid, open _smile._

Potter grinned widely, with a sort of ease that could have only belonged to the most carefree man on earth. And when he smiled, his whole face transformed—little wrinkles peppered the corners of his spectacled eyes, which seemed to glow like emeralds with excitement.

In that moment, Harry Potter's charisma was _blinding. _At least half of the room had paused in their potion-making, enraptured by it.

But it seemed he was oblivious to the attention he'd attracted. In the hand that wasn't holding a Quidditch broom, Potter was brandishing a paper filled with… magical signatures?

"We're holding Quidditch tryouts next week, and I just need your permission to hold them during the time slots I've allotted here."

He leaned back on his heels, hands fidgeting. So _childish, _Tom wanted to scoff, except that there was something almost magnetic about the way Potter moved—as if he was constantly buzzing with anticipation, adrenaline.

Slughorn took the papers from the older student, skimming through the papers with mild disinterest.

"And… what is it you require of me?"

And then, suddenly, Potter's posture seemed to change. He straightened up, crossing his arms. Energy and authority seemed to fly off of him, swirling in the potion-scented air.

"As I'll be accommodating every possible slot, I also need your permission to miss classes."

This, of course, broke Tom out his trance.

What kind of idiot put _Quidditch _over academics?

_This one, apparently, _Tom sneered, even as he continued to listen in on the conversation.

But Slughorn merely guffawed as he gestured Potter over. "My permission, Harry? I have a feeling that even if I were to deny it, you would still somehow find a way to miss classes and hold tryouts."

"... Probably, Sir," the older boy answered candidly, biting his lip as he grinned impishly. He relaxed, rubbing the back of his neck sheepishly. "I'm not exactly known for following the rules."

As Slughorn laughed some more in delight, Tom's impression of Potter continued to sink by the second. His jaw ticked in annoyance at how unreasonably, emotionally unpredictable the student was_ . _Potter went from joyful, to determined, to _shy _in the span of mere seconds.

"Oh, yes. That cannot be denied. You've broken rules within every aspect of school—even in Quidditch, when you joined the team as a first year. First one in a hundred years." Slughorn looked at him more closely, approvingly. "And now, as a fifth year, you've been appointed Gryffindor's newest Quidditch captain… by far the youngest of the four."

Slughorn leaned back in his chair, his gaze never leaving Potter. "Very impressive. Your parents must be so proud."

Potter's ears reddened. The Gryffindor girls in the classroom had long since abandoned working on their potions, choosing instead to giggle at the Quidditch captain in their presence. Even the Slytherin girls were throwing long glances in Harry Potter's direction, equal parts assessing and impressed.

Potter, for his part, seemed distinctly uncomfortable. His ears were still bright red as he ran a hand through his messy locks, clearing his throat.

"Thank you, Sir. Yeah, dad's pretty thrilled about it. But… errr… " Potter awkwardly gestured towards the papers he'd given Slughorn. "If you don't mind—"

Slughorn's hands waved carelessly. "Ah, yes, yes, I'll sign it, young man. But don't go running away just yet. I've got a little proposition for a young man like yourself."

_Proposition? _Tom bit his bottom lip in contemplation, eyeing Potter in interest himself.

Potter's eyebrows raised high as Slughorn fixed him with a piercing, evaluative look—like he was looking at a piece of rare meat at the grocery store.

By this point, Tom was poised expectantly at the edge of his desk, his hands visibly loose around the knife he'd been using to chop.

_Could it be… an invitation to the famous Slug Club?_

"Come by my office next evening," Slughorn said eventually, his fingers weaving together on the desk upon which he'd laid Potter's documents.

Potter stared.

"Okay."

Tom lost it.

Potter was undoubtedly being given an invitation to the most prestigious, _exclusive _club at Hogwarts—an invitation even Tom had sought since his second day at Hogwarts after learning about it from his older peers, after realizing just how many doors it could open for an orphaned mudblood like him—

And all Potter had to say was, _okay?_

Tom was fuming. His right hand clenched around the knife once more, unaware that it had slipped down the handle.

He was so absorbed in the actions of this oblivious, Quidditch-_ obsessed _little bastard that he didn't notice the violently bubbling cauldron beside his own. The quiet, muttered, "Oh _no," _of his bumbling idiot of a classmate was nothing but background buzz…

But Potter's eyes flashed in Tom's direction, widening dramatically.

And that was all the warning Tom got before Potter dove for him, his Quidditch reflexes kicking in as he flew over tables and cauldrons. He slammed Tom against the floor, his hard body pressing warmly into Tom's. Tanned arms were placed on either side of him, sheltering him as a nearby potion exploded in the area where he'd been standing seconds ago.

Tom blinked in shock, his eyes meeting the wide, green ones mere inches from his own.

A puff of breath against his forehead, and the scent of grass and treacle tart was overwhelming him.

"You okay?" Potter breathed, concern evident in his tone. He pushed off of Tom and stood up, running a hand through his flyaways before holding it out to the younger boy with that same stupid, warm smile.

_Why?_

Tom stayed frozen, his body unmovable. For once in his life, he couldn't think_ … _his mind was completely blank, processing nothing beyond sensations of grass and_"You okay?" _and messy, black hair that had clouded his vision mere seconds ago—

_Why had he helped Tom?_

And had that… had that actually been _concern _in his voi—?

"Hey," Potter said gently, looking at Tom with a sudden frown. "Wait a second."

To his complete appallment, Potter got down on his knees and reached out, his calloused fingers clasping Tom's smaller hand. He turned it over to reveal a bloody injury, caused by the cutting knife Tom had been squeezing before the incident.

Potter looked at him seriously. "Should I take you to the infi—"

Tom jumped into action, scrambling backwards. He'd never felt so disoriented in his life. But there was something about Potter that made him feel like he had to stay as_far away as possible._

"I'm fine," Tom lied tersely, snatching himself out of Potter's hand as he got up from the floor and dusted himself off. When Potter continued to stare at him with that revolting concern_ , _his hand still outstretched, he tossed Potter a narrow-eyed look.

"I. Am. _Fine, _" he gritted out in neat syllables.

Potter retracted his hand quickly then, raising his eyebrows at Tom's venomous tone. He merely shrugged before walking away as others approached them both to ensure that they were well.

Only once Potter was completely out of his sight did Tom take a deep breath, regaining his bearings and dampened sense of dignity right as Potions came to an end.

He tapped his idiotic neighbor on the shoulder.

"Longbottom," he said simply, calmly.

Neville Longbottom flinched, before stammering. "I-I didn't m-mean to—"

"You're _dead _," Tom seethed, a fraction of his pent-up emotions seeming to escape in that one last word, before turning on his heel and stalking out. And as he exited the classroom, he glimpsed Longbottom still shuddering in terror, in the same place he'd left him.

The very same kind of shudders Tom was suppressing right now.

Because Potter was possibly the first student to shower him with any sort of… Tom swallowed… _ kindness. _And the way he'd acted—caring, courteous, getting down on his _knees _for Tom like a perfect _gentleman— _it all made Tom's chest thud painfully.

That painful feeling in his chest never dissipated in the weeks that followed.

It tore at his gut, spreading across his limbs like molten lava until it reached his brain, his eyes, his nose, his mouth. And he couldn't see anything except for that kind, secret smile, couldn't smell anything except for treacle tart.

Tom could only hear the patter of rain between hallways_ . _It reminded him of the droplets that had clung to Potter's Quidditch attire as he'd walked into the Potions classroom, soaked and yet, so fresh-looking _… _looking like a new beginning, like hope, like _redemption…_

And if he listened to the wind closely enough, he could still hear that gruff whisper. That one breathy, mindless comment, puffed against Tom's shoulder, that had completely shaken his foundations.

_You okay?_

Tom turned the corner and grasped the wall, shoulders shaking as he sunk down against it. It was long past dinner time, nearing curfew, and taking a midnight stroll had only cluttered his mind further.

When he closed his eyes, the next image he saw was Potter's expressive mouth. That cocky grin, swiftly shifting into that concerned, sweet smile.

_You oka—?_

"Shut up!_ " _Tom snarled into the abandoned, dark hallways, hearing the crack in his own voice echo back. He clawed at the walls behind him, uncertain, confused, lost and lonely.

_Lonely, _a small inner voice muttered, _save for that voi—_

"No," he whispered raggedly, angrily.

Verdant green eyes. A large, warm hand encasing his own.

_You okay?_

A hard body protecting his own, pressing warmly against Tom in a cruel parody of a _hug _… something he'd never felt before, in any fashion, until Potter happened to him.

_You okay?_

Tom crumpled into a ball then, sliding down to the floor as his face screwing up in the shadows. Tears leaked from his eyes, even as Tom denied it—he couldn't possibly be crying. There was no way_—_he'd never cried a day in his _life—_

A violent sob tore through his sternum, wreaking havoc on his body, and then he fell eerily still.

No, he was most definitely_ not _okay.

Tom was _breaking._

. . .

Eventually, he gave in.

_Infatuation, _Tom mouthed, testing the word's weight on his tongue. It was illogical, and Tom knew it, and he _still _succumbed to it.

It was a strange feeling, surrendering to these new emotions.

Tom had always prided himself on his sense of control. Since a young age, he'd exercised precise control over his movements, over his magic… and even, to a certain degree, over his own mind. He'd found that suppressing all of his worthless emotions to the point where they ceased to exist allowed him to think and act with utter clarity.

But thoughts of _Harry_—_his savior, _whispered a small, weak voice in his head—had overpowered his defenses. They had continued to erode at his barriers for weeks on end until every waking moment was torture, a constant fight against these new _emotions _that barraged him like an army of Dementors.

And so, defeated by his own infatuation, Tom did what any other being would do in his position:

He stalked Harry.

Tom followed him in the hallways, observing how Harry rushed between classes. He was quite popular, frequently surrounded by a following of Gryffindors. But without fail, he was always sandwiched right between those two friends of his: the tall ginger and the nerdy brunette.

They were always whispering with each other, cracking unknown jokes that brought shared smiles to their faces. For the first time in his life, Tom found himself wanting to _understand _friendship… if only to comprehend the secret to making Harry smile like that at _him._

_Weasley _and _Granger._

_What was it about them, that Harry liked so much?_

Though they formed an odd trio, it was clear to Tom that they were the best of friends. They were quite protective of each other; Weasley and Granger stayed by Harry's side no matter what. Tom had often seen Harry rolling his eyes whenever his friends bristled, which occurred every time a squad of Slytherins happened to pass by.

"They've tried to sabotage you countless times, Harry!" Weasley cried once, waving his hands around frantically. "The Slytherins _know _they'll never win a match when you're playing!"

Granger added on, "He's right, Harry. Remember that dementor prank, during the match with Hufflepuff? You took a nearly fatal fall from over three hundred feet—you would have been killed if Professor Dumbledore hadn't—"

"Yeah! That's why Hufflepuff won that day. Your only loss, _ever. _" Weasley interrupted, shaking his head in misery. "Merlin, that was just _brutal— _"

"Ron!" Granger glared sternly at him. "Sometimes, I doubt whether you care more for Harry than Quidditch!"

"Hermione!" Weasley gasped, clutching a hand to his chest in fake horror. "Why _ever _would you make me choose?"

It was obvious that he'd been going for a joke. But from the way the Granger's eyes darkened in fury, it was clear that she had not _taken _it for one.

As the brunette and ginger began to bicker once more, Tom saw Harry stifle a snigger, quietly bearing the arguing. He always was the quietest of the three, content to just sit and listen in on conversations sometimes… which, lately, had often evolved into bickering.

Again, Tom had to wonder why Harry put up with those two.

Eventually, Harry decided to bring an end to his own misery.

"Guys, guys," he said, putting a hand on each of their shoulders. "That dementor prank was _two years ago. _Let's not get too worked up about it, eh?"

Harry cricked his neck, glancing away as his eyes followed a couple of younger Slytherins near the Great Hall. "Besides, I'm sure those Slytherins who used to prank us have matured a bit by now—enough to know—"

"_Matured? _" Weasley cried. "You think _maturing _would stop a Slytherin from being _evil? _" His eyes rolled up towards the ceiling. "That's like saying _growing up _would cause Fred and George to stop playing pranks!"

He threw his hands upwards, wailing, "And look what happened there. They opened a _joke shop! _"

Harry broke into laughter, as uncontrollable as the hair on his head, and Tom raised his eyebrows. It seemed that he found the Weasley brat's antics amusing.

Weasley shook his head, continuing on. "... despite the fact that they could have gone into any field. I mean, they had nearly perfect O.W.L. exam res—"

Weasley stopped, his face going white.

"O-O.W.L.s" he said simply.

Upon hearing that word, Granger seemed to literally _perk up. _She launched into a discussion on their study plan, which only served to make Weasley go positively green.

And Harry, aware and ever the middleman, bit his bottom lip—as if suppressing a grin—before comfortingly patting Weasley on the back.

"Relax, mate. We have _months. _Everything will be okay."

_Relax._

_You okay?_

_Everything will be okay._

Whenever he heard Harry talking like that, Tom—hidden in the bushes of the courtyard as he eavesdropped—felt an flood of calm wash over him.

And Harry was just as protective of his own friends. Whenever Crabbe and Goyle lumbered towards them, taunting Hermione for being such a _know-it-all mudblood, _he had his wand in their faces in an instant.

Though he rarely cursed anyone, the waves of fury that emanated from him were enough. Harry straightened up, his posture determined and fierce. His green eyes shot darts of heated poison, his crazy black locks growing wilder than ever.

When Harry Potter faced off with another, one look at those _Avada Kedavra _eyes was enough to make his opponents shudder.

"Don't you _dare _speak to my friends like that again."

That same deathly-quiet authority, Tom witnessed on the Quidditch fields.

He studied on the Quidditch bleachers after classes, during the Gryffindor Quidditch practice sessions… spreading out his books on the benches. Even when it rained, a slight repulsion charm around himself and his books was always enough to keep everything completely dry.

And out of the corner of his eye, Tom would observe Harry flying, commanding his teammates. He was a patient but thorough captain, repeating plays countless times until the team succeeded in performing them as a whole.

And when he flew_ …_

Harry put his _all _into it.

He wore an intense look of focus on his face with every dive, eyes narrowed and jaw clenched in concentration. And when he caught the snitch, Harry completely transformed—the light danced in his eyes, his features dripping with adrenaline and exhilaration as he held it up, grinning victoriously.

_Glorious._

Tom's breath hitched each time, unbeknownst to him… before he would remember himself, looking down at his books hastily.

His daily appearances at the Gryffindor practices didn't go unnoticed, of course.

At first, the team was suspicious of him.

"... spying for Slytherin?" a stocky, towheaded boy theorized out-loud, staring at Tom warily.

Harry had looked at Tom then, his eyes piercing and striking as ever. Tom had swallowed dryly, refusing to break eye-contact with the older boy.

After a few moments, Harry smiled at him, teeth glinting in the sunlight. He waved, and Tom was so shocked he forgot to wave back.

Then Gryffindor's captain looked away, shaking his head towards the others and saying, "Nah, he wouldn't. Let's just get back to playing. _Focus. _"

After days of Tom continuing to do nothing but sit and study, their hostility waned away. They even began greeting him cheerfully when they walked onto the field, and Tom would nod respectfully in turn.

He never spoke to them, however. Soon, they began to talk about him, in _front of him, _as if he were deaf…

_Shameless Gryffindors, _Tom tutted internally.

"Our one-man audience," they'd taken to calling him, almost affectionately.

The Gryffindor players paid him even more attention now… the _good _kind of attention, looking over to see Tom's reaction when they performed a particularly tricky play. But most of the time, unless it was Harry performing it, Tom wasn't paying attention at all.

This, too, the Gryffindors noticed.

And eventually, realization dawned on them. Slow and steady, like the rising of a baking cake.

Because how _sweet— _their little one-man audience had a crush on their captain.

With sly smiles, the teasing began.

"Oh, look! Harry!" one of the beaters called out as the team after practice had finished. "It's your girlfriend!"

Flushing at such a direct remark, Tom quickly looked down at his book once more. He could feel the burning weight of everyone's gazes—especially Harry's.

"Oi! Leave him alone," Harry said, a smile evident in his tone. "Can't you see the poor boy's trying to study?" He touched down on the ground, hiking his broom on his shoulder as he walked off.

"Oh, yes." A tall, black girl returned, smirking as she placed her hands on her hip. She tossed Tom a sly, knowing glance. "_ Study. _At the Quidditch pitches, instead of the library. He obviously has no ulterior motive of any kind _…"_

"Johnson," Harry said simply, his tone friendly but firm and warning. Authoritative.

And she quickly shut up. No one discussed it again. Their voices trailed off as they moved away from the pitch, practice over.

Stiff with mortification, Tom had packed his books and left the pitch along with them.

He managed to stay away for about a week before coming back.

Thus, that was how Tom's first year passed. He was quiet and unsuspecting, a mere mudblood whose only saving grace—in the eyes of his Slytherin peers—lay in the many points he earned through answering questions.

And there was the quiet, unspoken, universal truth that echoed across the hallways of Hogwarts—that Tom Riddle was infatuated with Harry Potter.

. . .

Tom's first year had been the quiet before the storm.

When he arrived back at Hogwarts for his second year, his crush had become the talk of Slytherin House. Whistles and taunts greeted him at every corner of the dorms, and his previous status as an intelligent but orphaned mudblood was somehow marred, even further, by his crush on a _Gryffindor._

If they hadn't before, Slytherin House downright _hated _Tom now.

He had to put an end to this.

Tom stopped going to the Quidditch field for good. He ceased following Harry in the hallways. He was less obvious about his obsession, tossing sideways glances at the older boy during meal times.

His hand curled around the fork as he forced himself to look down once more, during the Halloween Banquet. The reason he'd been so _obvious _in the first place… was because, perhaps, some part of him had wanted Harry to recognize him and feel something as well.

But Tom knew, realistically, that all he would get from Harry were those kind smiles. Nothing more. Harry had even stopped looking back at him during practices…_ dismissing him, _Tom realized with a pang.

He'd been such a _fool._

Months passed.

He discovered the Chamber of Secrets. His heritage.

It was enough to distract him from his folly and ridiculous attentions for Harry Potter. It was enough to motivate him, to embolden his efforts towards charming his own Slytherin peers… to regain their affections.

There was a monster brimming with potential, waiting to break free, and it wasn't just the Basilisk.

It was _him. _Tom. Destined for greatness.

He had lost focus, back then… but now he had it back. Countless hours spent practicing magic and reading in the library paid off.

By the end of his second year, Tom had spread the word of his ancestry, subtly commanding power within his own House. He had built a new image for himself, charming and polite, powerful and intelligent as ever. The _perfect _Slytherin.

Slytherins no longer referred to him as a _mudblood, _but as _Riddle… _fear and deference heavy in their tone.

But it still wasn't enough.

Vengeance burned in him, the cruelties from his youth unforgotten. Tom wanted them _bowing _at his feet for the names they'd called him, referring to him as a _superior, _ calling him _My Lord _in utmost awe…

But for now, their fear would do.

As for the knowledge of Tom's distasteful crush, it was washed into nonexistence.

Even Tom was able to stop thinking about _him._

… But not… completely.

He had stopped attending every match Gryffindor played. His image mattered now, image was _everything. _But sometimes, Tom would watch matches from the windows of the library, because he somehow always sat next to the side that overlooked the Quidditch pitch.

_Coincidence, _Tom told himself. _Mere habit, perhaps._

And if he did happen to walk behind Harry between classes, taking the longer way while he was at it—

Well. Who was going to catch him?

Indeed, his own obsession took longer to fade into nothingness. But finally, there were days when Tom begun to stop acknowledging Harry… weeks when he didn't think about _Harry _at all. Improvement was made… steadily… steadily…

Until a certain, stocky, black-haired figure ran into Tom at the corner of a hallway. All of the other boy's books spilled onto the floor.

_Imbecile._

"Let me get those for you," Tom said smoothly, suavely, bowing down to gather the other boy's books.

When he looked up again, it was to the sight of familiar, burning green eyes framed by wild, black locks.

Tom gasped.

It was like being hit by a car—all of those _ugly _emotions rushed back at him, tearing at him unrelentingly, unforgivingly.

"Thank you," Harry said quietly, unaware of Tom's inner turmoil as he took the books from his hands. Tom flinched as those fingers grazed his own.

A cocky smirk flirted with the edges of the older boy's mouth as he stood up, turning on his heel and leaving Tom to stare after him.

And then Tom was standing up as well, abruptly, an angry flush burning on his cheeks and down his neck. The _nerve _of him. Potter obviously hadn't forgotten Tom's little crush on him, even if everyone else had, and he'd taken advantage of it…

This incident, too, he resolved to wipe from his mind.

But then…

_But then…_

Something happened in Tom's third year. Something unimaginably horrible.

Harry Potter got a _girlfriend._

And everyone around him was going, _"Finally," _patting him on the back in the Great Hall, during the start-of-the-year banquet.

But _Tom…_

A monster roared in his chest, finally unleashed… a red-eyed beast with sharp fangs and all Tom could hear was _hissing, _he was so _furious. _He wished he'd already opened Chamber of Secrets—wished he'd already found it just so that he could beckon it, close enough to whisper, and command, "_Kill the girl."_

Tom found himself falling back into old habits. Stalking Harry. Learning more than he already did about every single one of his quirks.

And, of course, mealtimes were as prime an opportunity to observe Harry as ever.

As always, he was the perfect medium. Between Weasley gulping down bacon like air and Granger sipping at tea like she had hours to do so, Harry ate at a normal pace… but savored each bite like it was his last, enjoying it.

Harry was a man who appreciated. A man who found pleasure in the smallest things, _beauty _in the ugliest of things.

Beauty, in the _ugliest _of things.

Tom's face darkened as the petite, Asian girl leaned over to give Harry a kiss, watching as Harry leaned in with a soft smile _that should have been Tom's, only Tom's—_

His period of denial was long-over. Tom had never gotten over Harry Potter. He never would.

Harry was _his._


End file.
